1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
kolezko [41]
3 years ago
5

Six dogs pull a two-person sled with a total mass of 220 kg. The coefficient of kinetic friction between the sled and the snow i

s 0.08. The sled accelerates from rest at 0.75 m/s2 until it reaches a speed of 12 km/h. a) What is the work done by the dogs in the accelerating phase? b) What is the maximum power output by the dogs? c) What is the pulling force from the dogs (assumed to be horizontal)?
Physics
1 answer:
irina [24]3 years ago
4 0

Answer:

a) 2457J

b) 558W

c) 337N

Explanation:

Assuming dogs started from rest.

v=a*t\\t=\frac{a}{v}\\v=12\frac{km}{h}\frac{1000m}{km}*\frac{1h}{3600s}\\\\v=3.3m/s\\\\t=\frac{3.3m/s}{0.75m/s^2}\\t=4.4s

and the displacement is given by:

d=\frac{1}{2}*a*t^2\\d=7.3m

Using the energy conservation formula:

K_i+U_i+W_d+W_f=K_f+U_f

Because the motion started from rest the initial kinetic energy is zero, the motion occurred in-ground level so the gravitational energy is zero too.

the work done by the friction force is given by:

W_f=F_f*d*cos(\theta)\\W_f=\µ*m*g*d*cos(180)\\W_f=0.08*220kg*9.8m/s^2*7.3m*(-1)\\W_f=-1259J

so:

W_d=\frac{1}{2}*220kg*(3.3m/s)^2+1259J\\W_d=2457J

The power is given by:

P=\frac{W}{t}\\\\P=\frac{2457J}{4.4s}\\\\P=558W

and the force exerted by the dogs:

W_d=F_d*d*cos(\theta)\\F_d=\frac{W_d}{d*cos(0)}\\\\F=\frac{2457J}{7.3m*(1)}\\\\F=337N

You might be interested in
Tarzan, whose mass is 94 kg, is hanging at rest from a tree limb. Then he lets go and falls to the ground. Just before he lets g
zalisa [80]

Answer:

(a) 6.26 m/s

(b) ‭-2,118.76 J

Explanation:

Here we have

Tarzan's mass, m = 94 kg

Height of feet above ground, h₁ = 2.0 m

Height of center of mass above ground = 2.8 m

Height of center of mass on the ground, h₂ = 2.8 - 2.0 = 0.8 m

Height of center of mass in the crouched position, h₃ = 0.5 m

(a) The speed at the instant just before Tarzan's feet touches the ground is given by;

v² = u² + 2·g·h₁

v = Speed at the instant just before Tarzan's feet touches the ground

u = Initial speed = 0 m/s while hanging from the tree

g = Acceleration due to gravity

Therefore, v² =  2·g·h₁ = 2 × 9.8 × 2 = 39.2 m²/s²

∴ v = √(39.2 m²/s²) = 6.26 m/s

(b) Here we have

Just before Tarzan's feet touches the ground internal energy is given by;

Initial Internal energy = K.E. + P.E. = m·g·h₂+ 0.5·m·v²

= 94 × 9.8 × 0.8 + 0.5 × 94 × 39.2 = ‭2,579.36 J

When in the crouched position, the final internal energy is given by;

m·g·h₃ = 94 × 9.8 × 0.5 = 460.6 J

Therefore net change in internal energy, ΔU is given by

ΔU = Final internal energy - Initial internal energy

ΔU = 460.6 J - 2,579.36 J  = ‭-2,118.76 J.

4 0
3 years ago
three different-mass projectiles are launched at different angles of elevation from the top of a building. each particle has the
MrRa [10]

The correct option is b. The one with the lowest mass.

An object's kinetic energy is determined by

k=1/2mv^2

where

m is the object's mass.

v is the object's speed.

The three missiles in this puzzle have varying masses but the same beginning kinetic energy.

The three projectiles will all have the same kinetic energy when they hit the ground because mechanical energy is conserved, assuming there is no air resistance (because the potential energy that they have lost is the same, since they have been launched from the same height, and they reach the same final altitude, the ground).

hence,

K1=k2=k3

To know more about kinetic energy refer to brainly.com/question/14604194

#SPJ4

3 0
1 year ago
Power is work done over a what?
melomori [17]
No the answer is energy 
4 0
3 years ago
1. Given an element's atomic number and mass number, how can you tell the number of protons and neutrons in its nucleus?
DanielleElmas [232]
C. Number of protons = atomic number; number of neutrons = mass number - atomic number
8 0
2 years ago
Read 2 more answers
Brainly app · Installed
Sauron [17]
I need a picture plz I don’t know what to answer.
6 0
3 years ago
Other questions:
  • 1. Line segment AC touches the circle at a single point B. Line segment OB extends through the center of the circle.
    7·1 answer
  • Make a general statement concerning how large bodies of water affect the climate of nearby coastal communities.
    5·1 answer
  • Explain why liquids flow but solids do not.
    10·2 answers
  • You wish to boil 1.9 kg of water, which has a specific heat capacity of 4186 J/kg-K. The water is initially at room temperature
    15·1 answer
  • The drawing shows a person looking at a building on top of which an antenna is mounted. The horizontal distance between the pers
    11·1 answer
  • A spherical balloon is partially blown up and its surface area is measured. More air is then added, increasing the volume of the
    13·1 answer
  • Help me plsssssssss!!]
    11·1 answer
  • A block of mass m is attached to the end of a spring (spring stiffness constant k ). The mass is given an initial displacement x
    12·1 answer
  • Two identical conducting spheres are charged with a net charge of +5.0 q on the first sphere and a net charge of −8.0 q on the s
    10·1 answer
  • Physics teacher guide grade 9​
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!